1. Field of the Invention
The invention relates to sheet item delaminating apparatus and more particularly to a four bar linkage for use as an automatic delaminating mechanism for lifting sheet items from an electrostatically energized photo sensitized receptor drum for a copying apparatus.
2. Description of the Prior Art
Most electrographic printing/copying apparatus employs some means for detacking or delaminating the "copy" from the photo-receptor drum to which the sheet item has invariably become electrostatically attracted. Edge aligned item stripper belts moving in the same direction as the item have been employed and are effective to detac the item but obviously limit the edge to edge printing area of the apparatus. Continuously contacting doctor blades have also been used but they tend to score the delicate surface of the photo receptor drum and ultimately destroy copy legibility.
Some copy apparatus have utilized a stripper finger recessed in a circular peripheral groove located in the edge of the photo-receptor drum. This technique also limits the edge to edge printing/copying by the fixed amount of drum space taken up by the groove or grooves therein.
Another technique employs a vacuum method whereby the uppermost sheet item is literally sucked off the photo-receptor drum. Still another mechanism utilizes the Bernoulli effect in which a sudden blast of air causes a low pressure area across the top of the item effective to produce a low pressure area on the order of a vacuum which detacs or delaminates the item off the drum. These latter techniques require relatively expensive and bulky vacuum pumps or blowers. In addition they are fairly noisy.
It is an object therfore of the present invention to provide apparatus which overcomes these and other associated problems in a new, novel and unobvious manner.